public class Text5 {
    public static int getVal(char ch){
        switch(ch){
            case'I':return 1;
            case'V':return 5;
            case'X':return 10;
            case'L':return 50;
            case'C':return 100;
            case'D':return 500;
            case'M':return 1000;
            default:return 0;
        }
    }

    public static int romanToInt(String s) {
        char[] str = s.toCharArray();
        int sum = 0;
        int preNum = getVal(str[0]);
        for(int i = 1;i < s.length(); i ++) {
            int num = getVal(str[i]);
            if(preNum < num) {
                sum -= preNum;
            } else {
                sum += preNum;
            }
            preNum = num;
        }
        sum += preNum;

        return sum;
    }

    public static void main(String[] args) {
        String s = "MCMXCIV";
        int ret = romanToInt(s);
        System.out.println(ret);
    }
}
